Effectiveness of the bond established between ceramic inlays and dentin using different luting protocols.

Abstract

To evaluate the ceramic-to-dentin bond following luting with light- and dual-curing resin composites using different adhesive techniques. Dentin surfaces from 160 human molars were ground flat and randomly divided into eight groups (n = 20). Vita Mark II ceramic disks measuring 2 and 4 mm in thickness were bonded to the dentin with one of the following luting systems: Syntac/Tetric Ceram (ST), Syntac/Variolink II (SV), OptiBond Solo Plus/ Prodigy (OP), OptiBond Solo Plus/Nexus 2 (ON). Two different irradiation times (60 s, 120 s) were used per luting system, each without (-PC) and with (+PC) precuring the respective adhesive layer. After storage in water for 24 h at 37°C, the bonded specimens were sectioned perpendicularly to the adhesive interface into 1-mm-thick sticks. Three sticks per specimen were loaded to failure under tension in the Zwicki 1120. Failure analysis was performed using a scanning electron microscope (SEM). Four-way ANOVA showed that the ceramic thickness, the type of luting system used, and the adhesive precuring had a significant effect on the microtensile bond strength. The longer irradiation times did not significantly increase the bond strength. The highest values were recorded with SV/+PC (27.9 ± 4.3 MPa) and the lowest with ST/-PC (10.2 ± 3.5 MPa). Under the SEM, failed specimens that had not been precured showed significantly more exposed dentin than those which had been precured (chi-square test). The precuring step of light-curing bonding systems and the use of dual-curing luting composites were shown to optimize the dentin bond under thick ceramic layers.